[BZOJ1095][ZJOI2007]Hide 捉迷藏

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <stack>
#include <vector>
#include <queue>
#include <cstring>
#include <string>
#include <map>
#include <set>
using namespace std;

const int BufferSize = 1 << 16;
char buffer[BufferSize], *Head, *Tail;
inline char Getchar() {
	if(Head == Tail) {
		int l = fread(buffer, 1, BufferSize, stdin);
		Tail = (Head = buffer) + l;
	}
	return *Head++;
}
int read() {
	int x = 0, f = 1; char c = Getchar();
	while(!isdigit(c)){ if(c == ‘-‘) f = -1; c = Getchar(); }
	while(isdigit(c)){ x = x * 10 + c - ‘0‘; c = Getchar(); }
	return x * f;
}

#define maxn 100010
#define maxm 200010
#define maxlog 18

int n, m, head[maxn], nxt[maxm], to[maxm];

void AddEdge(int a, int b) {
	to[++m] = b; nxt[m] = head[a]; head[a] = m;
	swap(a, b);
	to[++m] = b; nxt[m] = head[a]; head[a] = m;
	return ;
}

int mnd[maxlog][maxn<<1], clo, dfn[maxn], dep[maxn], Log[maxn<<1];
void build(int u, int pa) {
	dfn[u] = ++clo;
	mnd[0][clo] = dep[u];
	for(int e = head[u]; e; e = nxt[e]) if(to[e] != pa)
		dep[to[e]] = dep[u] + 1, build(to[e], u), mnd[0][++clo] = dep[u];
	return ;
}
void rmq_init() {
	Log[1] = 0;
	for(int i = 2; i <= clo; i++) Log[i] = Log[i>>1] + 1;
	for(int j = 1; (1 << j) <= clo; j++)
		for(int i = 1; i + (1 << j) - 1 <= clo; i++)
			mnd[j][i] = min(mnd[j-1][i], mnd[j-1][i+(1<<j-1)]);
	return ;
}
int cdist(int a, int b) {
	int l = dfn[a], r = dfn[b];
	if(l > r) swap(l, r);
	int t = Log[r-l+1];
	return dep[a] + dep[b] - (min(mnd[t][l], mnd[t][r-(1<<t)+1]) << 1);
}

int rt, size, f[maxn], siz[maxn];
bool vis[maxn];
void getroot(int u, int pa) {
	siz[u] = 1; f[u] = 0;
	for(int e = head[u]; e; e = nxt[e]) if(to[e] != pa && !vis[to[e]]) {
		getroot(to[e], u);
		siz[u] += siz[to[e]];
		f[u] = max(f[u], siz[to[e]]);
	}
	f[u] = max(f[u], size - siz[u]);
	if(f[rt] > f[u]) rt = u;
	return ;
}
void dfs(int u, int pa) {
	siz[u] = 1;
	for(int e = head[u]; e; e = nxt[e]) if(to[e] != pa && !vis[to[e]])
		dfs(to[e], u), siz[u] += siz[to[e]];
	return ;
}
int fa[maxn];
void solve(int u) {
	vis[u] = 1;
	for(int e = head[u]; e; e = nxt[e]) if(!vis[to[e]]) {
		dfs(to[e], u);
		f[rt = 0] = size = siz[to[e]]; getroot(to[e], u);
		fa[rt] = u; solve(rt);
	}
	return ;
}

priority_queue <int> tofa[maxn], tofa_del[maxn], son[maxn], son_del[maxn], ans, ans_del;
bool has[maxn];
void tofadel(int u, int d) {
	tofa_del[u].push(d);
	while(!tofa[u].empty() && !tofa_del[u].empty() && tofa[u].top() == tofa_del[u].top())
		tofa[u].pop(), tofa_del[u].pop();
	return ;
}
void sondel(int u, int d) {
	son_del[u].push(d);
	while(!son[u].empty() && !son_del[u].empty() && son[u].top() == son_del[u].top())
		son[u].pop(), son_del[u].pop();
	return ;
}
void ansdel(int d) {
	ans_del.push(d);
	while(!ans.empty() && !ans_del.empty() && ans.top() == ans_del.top())
		ans.pop(), ans_del.pop();
	return ;
}
int upans(int u) {
	if(son[u].empty()) return -1;
	int t1 = son[u].top(); son[u].pop();
	while(!son[u].empty() && !son_del[u].empty() && son[u].top() == son_del[u].top())
		son[u].pop(), son_del[u].pop();
	if(son[u].empty()){ son[u].push(t1); return -1; }
	int t2 = son[u].top();
	son[u].push(t1);
	return t1 + t2;
}
void update(int s) {
	int tmp = upans(s);
	if(tmp >= 0) ansdel(tmp);
	if(!has[s]) son[s].push(0);
	else sondel(s, 0);
	tmp = upans(s);
	if(tmp >= 0) ans.push(tmp);
	for(int u = s; fa[u]; u = fa[u]) {
		int d = cdist(s, fa[u]);
		tmp = upans(fa[u]);
		if(tmp >= 0) ansdel(tmp);
		if(!has[s]) {
			if(tofa[u].empty()) son[fa[u]].push(d);
			else if(tofa[u].top() < d) sondel(fa[u], tofa[u].top()), son[fa[u]].push(d);
			tofa[u].push(d);
		}
		else {
			tofadel(u, d);
			if(tofa[u].empty()) sondel(fa[u], d);
			else if(tofa[u].top() < d) sondel(fa[u], d), son[fa[u]].push(tofa[u].top());
		}
		tmp = upans(fa[u]);
		if(tmp >= 0) ans.push(tmp);
	}
	has[s] ^= 1;
	return ;
}

int main() {
	n = read();
	for(int i = 1; i < n; i++) {
		int a = read(), b = read();
		AddEdge(a, b);
	}
	
	build(1, 0);
	rmq_init();
	f[rt = 0] = size = n; getroot(1, 0);
	solve(rt);
	for(int i = 1; i <= n; i++) update(i);
	
	int q = read();
	while(q--) {
		char cmd = Getchar();
		while(!isalpha(cmd)) cmd = Getchar();
		if(cmd == ‘G‘) printf("%d\n", ans.empty() ? -1 : ans.top());
		else update(read());
	}
	
	return 0;
}